For a photodetecting semiconductor device such as a photodetecting phototransistor, a photodiode, or a photocoupler, a photodetecting semiconductors device as shown in FIGS. 1 and 2 called “surface mount type” and “insertion mount type” have been used. In these devices, the photodetecting semiconductor device placed on a lead electrode is encapsulated with a transparent resin, and most products have been encapsulated with an epoxy resin. However, such use of the epoxy resin is facing the problem of discoloration at high temperature since solder reflowing is recently carried out at a higher temperature due to the prohibition of the use of lead solder corresponding to the requirement of reducing the stress on the environment.
FIGS. 1 and 2 shows a photodetector 1, a silicone die bonding material 2, leads 3 and 4, a gold wire 5, a cured resin composition of epoxy-silicone mixture 6, and a ceramic casing 7.
Semiconductor elements such as a photodetector have been secured to a lead flame, a ceramic substrate, or an organic substrate by using an epoxy adhesive (die bonding material), and covered and protected with an epoxy resin such as a bisphenol A epoxy resin or an alicyclic epoxy resin and an acid anhydride curing agent which is transparent after curing (Patent Document 1: JP-B2 3241338, Patent Document 2: JP-A 7-25987). However, silicone rubber compositions having a higher heat and light resistance are recently used for the LED encapsulation. These silicone rubber compositions, however, suffer from the problem of surface tackiness, and hence, dust deposition when used for coating an electric and electronic parts.
In the meanwhile, silicone varnish which has obviated the problems as described above have been developed. The silicone varnish, however, suffered from crack generation. Accordingly, a silicone composition which provides a cured product which does not suffer from dust deposition when used in packaging an electric or electronic part, and which exhibits excellent crack resistance and impact strength is highly awaited. Also demanded is a silicone resin composition which is solid at room temperature and which can be cured by transfer molding and compression molding in conventional apparatus.
Prior art which may be related to the present invention are disclosed in the documents as described above and also in the following documents.
[Patent Document 1] JP-B2 3241338
[Patent Document 2] JP-A 7-25987
[Patent Document 3] JP-A 2005-76003
[Patent Document 4] JP-A 2004-339482 corresponding to U.S. Pat. No. 7,019,100